Author Topic: Accuracy of GPS coordinates  (Read 2744 times)

Offline AnnieP

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Accuracy of GPS coordinates
« on: March 01, 2017, 05:35:19 AM »
I am running Photo Mechanic Version 5.0, build 18040 (9e75cf5), Mac OS 10.12.3.

I use PM to set GPS coordinates regularly. I have usually entered the coordinates in the top left of the entry window - Latitude Degrees and Longitude Degrees, then change Longitude to West. Recently I found it easier to enter the coordinates in the right side of the window, below the map, then hit GET GPS and ACCEPT. Then I noticed that the coordinates I entered below the map were not exactly the coordinates that carried over to the left side of the entry window. Granted, they are close, but I would rather they be exact.

Attached is an example. In this case, the coordinates are off by 0.2 miles.

Many thanks for any light you can shed on this.


Offline Kirk Baker

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Re: Accuracy of GPS coordinates
« Reply #1 on: March 01, 2017, 08:15:50 AM »
I am running Photo Mechanic Version 5.0, build 18040 (9e75cf5), Mac OS 10.12.3.

I use PM to set GPS coordinates regularly. I have usually entered the coordinates in the top left of the entry window - Latitude Degrees and Longitude Degrees, then change Longitude to West. Recently I found it easier to enter the coordinates in the right side of the window, below the map, then hit GET GPS and ACCEPT. Then I noticed that the coordinates I entered below the map were not exactly the coordinates that carried over to the left side of the entry window. Granted, they are close, but I would rather they be exact.

Attached is an example. In this case, the coordinates are off by 0.2 miles.

Many thanks for any light you can shed on this.

PM is querying the coordinates of the pin on the map.  It appears that they differ from what you entered.  I'll look into it, but in the meantime you should go back to your old method.

-Kirk

Offline AnnieP

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Re: Accuracy of GPS coordinates
« Reply #2 on: March 01, 2017, 08:26:25 AM »
But the pin is entered from the coordinates I input. Why would it be different?

I will definitely go back to the old method. It's just easier to use cut and paste in the larger box.

Please let me know if you find any reason for the behavior I described.

Thank you very much. I use PM all the time and rely on it.

Offline Kirk Baker

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Re: Accuracy of GPS coordinates
« Reply #3 on: March 01, 2017, 09:03:25 AM »
But the pin is entered from the coordinates I input. Why would it be different?

I don't know and can't know until I investigate the problem.

-Kirk

Offline Kirk Baker

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Re: Accuracy of GPS coordinates
« Reply #4 on: March 02, 2017, 04:05:11 PM »
Annie,

OK, so the problem is that the text you enter is interpreted by the Google Maps API 'geocode' which understands both addresses and coordinates, but what it does is it takes coordinates and snaps them to the nearest place (which is nearby but is not exactly at that coordinate pair.)

I have added code to parse the coordinates and if they seem reasonable it uses them directly, otherwise it hands them off to geocode() to attempt a conversion.

I tried it with your example coordinates and they're exactly the same to several decimal places.

Please give it a try.  The change was on the server that hosts the map so no update to PM is required.

Thanks,

-Kirk

Offline AnnieP

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Re: Accuracy of GPS coordinates
« Reply #5 on: March 02, 2017, 05:41:48 PM »
Kirk:

Thanks very much. I have some work to do tonight, will try that method and let you know how it does.

Again, many thanks for great support of a superior product.

Annie